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| United States Patent |
5,237,031
|
|
Kubota
, et al.
|
August 17, 1993
|
Organic solid electrolyte
Abstract
An organic solid electrolyte is disclosed, which comprises a high molecular
compound having a recurring unit represented by following formula (I), a
nonprotonic polar solvent, and a salt of a metal ion belonging to group Ia
or group IIa of the Periodic Table:
##STR1##
wherein R.sub.1 represents a hydrogen atom, a lower alkyl group, a cyano
group, or a chlorine atom; R.sub.2 represents a lower alkyl group, an
alkenyl group, an aryl group, or an aralkyl group; X represents --CO.sub.2
--,
##STR2##
--OCO--, or --O--, (wherein R.sub.3 represents a hydrogen atom or a lower
alkyl group); L represents an alkylene group; a represents 0 or 1; and m
represents an integer of from 0 to 5.
| Inventors:
|
Kubota; Tadahiko (Kanagawa, JP);
Yasunami; Shoichiro (Kanagawa, JP)
|
| Assignee:
|
Fuji Photo Film Co., Ltd. (Kanagawa, JP)
|
| Appl. No.:
|
652759 |
| Filed:
|
February 8, 1991 |
Foreign Application Priority Data
| Feb 09, 1990[JP] | 2-30318 |
| Mar 27, 1990[JP] | 2-78531 |
| Current U.S. Class: |
526/305; 252/62.2; 429/213; 429/307; 526/173; 526/303.1; 526/310; 526/312; 526/319; 526/326; 526/328.5 |
| Intern'l Class: |
C08F 120/54; H01M 006/16; H01M 006/18 |
| Field of Search: |
429/192
526/305,173,312,326
252/62.2
|
References Cited
U.S. Patent Documents
| 4654279 | Mar., 1987 | Bauer | 429/192.
|
| 4822701 | Apr., 1989 | Ballard | 429/192.
|
| 4830939 | May., 1989 | Lee | 429/192.
|
Primary Examiner: Schofer; Joseph L.
Assistant Examiner: Zitomer; Fred
Attorney, Agent or Firm: Sughrue, Mion, Zinn, Macpeak & Seas
Claims
What is claimed is:
1. An organic solid electrolyte comprising a high molecular compound having
a recurring unit represented by following formula (I), a nonprotonic polar
solvent, and a salt of a metal ion belonging to group Ia or group IIa of
the Periodic Table:
##STR28##
wherein R.sub.1 represents a hydrogen atom, a lower alkyl group, a cyano
group, or a chlorine atom; R.sub.2 represents a lower alkyl group, an
alkenyl group, an aryl group, or an aralkyl group; X represents --CO.sub.2
--,
##STR29##
--OCO--, or --O--, (wherein R.sub.3 represents a hydrogen atom or a lower
alkyl group); L represents an alkylene group; a represents 0 or 1; and m
represents an integer of from 0 to 5.
2. The organic solid electrolyte of claim 1, wherein the organic solid
electrolyte is formed in a thin film form.
3. An organic solid electrolyte comprising a high molecular matrix composed
of a monomer represented by the following formula (II) and a monomer
represented by the following formula (III), a nonprotonic polar solvent,
and a salt of a metal ion belonging to group Ia or group IIa of the
Periodic Table:
##STR30##
wherein R.sub.1 represents a hydrogen atom, a lower alkyl group, a cyano
group, or a chlorine atom; R.sub.2 represents a lower alkyl group, an
alkenyl group, an aryl, group, or an aralkyl group; X represents
--CO.sub.2 --,
##STR31##
--OCO--, or --O-- (wherein R.sub.3 represents a hydrogen atom or a lower
alkyl group); L represents an alkylene group; a represents 0 or 1; and m
represents an integer of from 0 to 5;
##STR32##
wherein Y represents an l-valent atomic group composed of carbon or carbon
and hydrogen; a' represents 0 or 1; l represents an integer of at least 2;
and R.sub.1, L, X, and a are the same as in formula (II).
4. The organic solid electrolyte of claim 3, wherein the organic solid
electrolyte is formed in a thin film form.
5. The organic solid electrolyte of claim 2 or 4, wherein the thin film is
formed by a heating method.
6. The organic solid electrolyte of claim 1 or 3, wherein the organic solid
electrolyte is filled in a porous film having a mean pore size of at least
0.15 .mu.m to form a thin film.
7. The organic solid electrolyte of claim 6, wherein the porous film is
composed of polyolefin.
8. The organic solid electrolyte of claim 6 or 7, wherein the thin film is
formed by a heating method.
Description
FIELD OF THE INVENTION
This invention relates to an organic solid electrolyte, and more
particularly to an organic solid electrolyte suitable for antistatic
materials, galvanic cells, and as materials for other electrochemical
devices.
BACKGROUND OF THE INVENTION
For applying a solid electrolyte to electrochemical devices such as
antistatic materials, (galvanic) cells, etc., it is necessary that the
solid electrolyte not only has a good ionic conductivity but also is
excellent in film forming property, has good storage stability, and can be
easily produced. However, a solid electrolyte satisfying all these
necessary requirements has not yet been developed.
For example, it is known that the inorganic solid electrolytes shown by
Na--.beta.--Al.sub.2 O.sub.3 and Na.sub.1+x Zr.sub.2 P.sub.3-x Si.sub.x
O.sub.12 (0.ltoreq.X.ltoreq.3) have a good ion conductivity as described
in M.S. Whittingham, Journal of Chemical Physics, Vol. 54, 414 (1971) and
A. Clearfield, et al., Solid State Ionics, Vol. 9/10, 895 (1983) but these
inorganic solid electrolytes have fatal faults that they have a very weak
mechanical strength and are inferior in fabricability into a flexible
film.
It is reported the polyethylene oxide (hereinafter, is referred to as PEO)
forms a complex functioning as a solid electrolyte with a salt of a metal
ion belonging to group Ia or group IIa of the Periodic Table, such as
LiCF.sub.3 SO.sub.3, LiI, LiClO.sub.4, NaI, NaCF.sub.3 SO.sub.3, KCF.sub.3
SO.sub.3, etc., and these complexes have a relatively good ion
conductivity in P. Vashista et al., Fast Ion Transport in Solid, 131
(1979) and also these complexes have a viscoelasticity and flexibility
specific to a polymer, a good workability, and also good storage
stability. However, since PEO has a large temperature reliance, although
the aforesaid complex may show a good ionic conductivity at a temperature
of 60.degree. C. or higher, the ionic conductivity thereof is greatly
deteriorated at about room temperature and hence it is difficult to use
the aforesaid complexes for products which can be used in a wide
temperature range.
Thus, for solving the faults of PEO, various PEO-modified polymers have
been proposed. For example, there are a vinylic polymer having a PEO group
at the side chain described in D.J. Banister et al., Polymer, Vol. 25,
1600 (1984), a polyphosphagen having a PEO group at the side chain
described in D. F. Shriver et al., Journal of American Chemical Society,
Vol. 106, 6854 (1984), and a material formed by introducing a low
molecular weight PEO group into a part of polysiloxane described in
Watanabe et al., Journal of Power Sources, Vol. 20, 327 (1987), etc.
However, these PEO-modified polymers have a low ion conductivity and cannot
be practically used.
Thus, for improving the ionic conductivity of polymers at room temperature,
materials composed of gels of high molecular compounds carrying an ionic
conductor have been recently actively investigated.
For example, JP-B-57-9671 (the term "JP-B" as used herein refers to an
"examined Japanese patent publication") discloses a material formed by
dissolving polymethyl methacrylate (herein after, is referred to as PMMA)
in propylene carbonate (hereinafter, is referred to as PC) and then
gelling the solution by heating. However, in order to increasing the ionic
conductivity of the aforesaid material to a practically usable level, it
is required to use a large amount of PC, which results in greatly reducing
the film strength of the material, whereby the material cannot function as
a solid electrolyte.
Also, materials using acrylate or methacrylate polymers having various
functional groups as a gelling agent for a nonaqueous solvent are
disclosed in JP-A-62-20262, JP-A-62-20263, JP-A-62-22375, JP-A-62-22376,
JP-A-62-219468, and JP-A-62-219469 (the term "JP-A" as used herein refers
to a "published unexamined Japanese patent application"), but these
materials also have the aforesaid problems and materials having both a
high ionic conductivity and an excellent film forming property have not
yet been developed.
Also, JP-A-63-135477 shows a material composed of a crosslinked high
molecular matrix having a PEO group carrying a low molecular weight liquid
PEO but the ionic conductivity of the material cannot be over a low value
of about 10.sup.-4 s/cm, which is the ionic conductivity of a liquid PEO
and the material is unsuitable for use as practical devices.
Furthermore, materials obtained by impregnating a high molecular matrix
having a polar group at the side chain with a nonprotonic polar solvent
such as PC are disclosed in U.S. Pat. Nos. 4,822,701 and 4,830,939 but in
these materials, a large amount of the solvent is required for increasing
the ionic conductivity, thereby the problem of greatly reducing the film
forming property cannot be solved, and hence the material is also
unsuitable for practical use.
Also, for the viewpoint of improving the film forming property, materials
obtained by impregnating porous films such as nonwoven fabrics with a high
molecule electrolyte are described in JP-A-63-40270 and JP-A-63-102104 but
since the ionic conductivity of these materials depends upon the high
molecule electrolyte itself, the materials have a fatal fault that the
ionic conductivity is very low. Furthermore, a material composed of a
porous film having small pore sizes carrying therein an ionic conductor is
disclosed in U.S. Pat. No. 4,849,311 but for carrying a liquid ionic
conductor, it is necessary to considerably reduce the pore sizes, whereby
the interfacial resistance thereof with an electrode material, etc., is
greatly increased and hence the material is also unsuitable for practical
use.
As described above, conventionally known solid electrolytes cannot meet the
whole problems that the ionic conductivity at about room temperature is
very low and the film forming property is very inferior or the interfacial
resistance with an electrode material, etc., is very large and hence the
provision of a solid electrolyte solving the whole problems has been
desired.
SUMMARY OF THE INVENTION
The object of this invention is, therefore, to provide a novel organic
solid electrolyte showing a high ionic conductivity even at a temperature
of near room temperature, having an excellent film forming property,
showing less interfacial resistance with an electrode material, etc., and
having an excellent liquid leakage resistance.
As the results of various investigations for solving the aforesaid problems
in conventional solid electrolytes, the inventors have discovered that the
aforesaid object can be achieved by the present invention as set forth
hereinbelow.
That is, according to this invention, there is provided an organic solid
electrolyte comprising a high molecular compound having a recurring unit
represented by the following formula (I), a nonprotonic polar solvent, and
a salt of a metal ion belonging to group Ia or group IIa of the Periodic
Table:
##STR3##
wherein R.sub.1 represents a hydrogen atom, a lower alkyl group, a cyano
group, or a chlorine atom; R.sub.2 represents an alkyl group (including
methyl, ethyl, propyl, and butyl), an alkenyl group, an aryl group, or an
aralkyl group;
X represents --CO.sub.2 --,
##STR4##
--OCO--, or --O--, (wherein R.sub.3 represents a hydrogen atom or an alkyl
group (including methyl, ethyl, propyl and butyl); L represents an
alkylene group; a represents 0 or 1; and m represents an integer of from 0
to 5.
According to one embodiment of this invention, the organic solid
electrolyte described above is in a thin film form.
According to another embodiment of this invention, there is further
provided an organic solid electrolyte comprising a high molecular matrix
composed of a monomer represented by the following formula (II) and a
monomer represented by the following formula (III), a nonprotonic polar
solvent, and a salt of a metal ion belonging to group Ia or group IIa of
the Periodic Table:
##STR5##
wherein R.sub.1 represents a hydrogen atom, a lower alkyl group, or a
chlorine atom; R.sub.2 represents an alkyl group (including methyl, ethyl,
propyl, and butyl), an alkenyl group, an aryl group, or an aralkyl group;
X represents --CO.sub.2 --,
##STR6##
--OCO--, or --O-- (wherein R.sub.3 represents a hydrogen atom or an alkyl
group (including methyl, ethyl, propyl, and butyl)); L represents an
alkylene group; a represents 0 or 1; and m represents an integer of from 0
to 5;
##STR7##
wherein Y represents an l-valent atomic group composed of carbon or carbon
and hydrogen; a, represents 0 or 1; l represents an integer of 2 or more;
and R.sub.1, L, X, and a are same as in formula (II).
According to other embodiment of this invention, the organic solid
electrolyte in the aforesaid embodiment is in a thin film form.
In the case that the organic solid electrolyte of this invention is in a
thin film form, the thin film is formed by heating.
Also, in the case that the organic solid electrolyte of this invention is
in a thin film form, the thin film is formed by filling the organic solid
electrolyte into a porous film having a mean pore size of at least 0.15
.mu.m.
In the aforesaid case of this invention, the porous film is composed of
polyolefin.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic sectional view showing an example of the galvanic
cell prepared in Example 7,
FIG. 2 and FIG. 3 are graphs showing the results of the changes of the
discharging capacities by the charging and discharging tests in Example 7
and Comparative Example 12,
FIG. 4 is a view showing the structure of the galvanic cell prepared in
Example 8, and
FIG. 5 and FIG. 6 are graphs showing the results of the changes of the
discharging capacities by the charging and discharging tests in Example 8
and Comparative Example 13.
DETAILED DESCRIPTION OF THE INVENTION
Then, the present invention is described in detail.
The organic solid electrolyte of this invention in the first embodiment
comprises a nonionic conductive high molecular compound, a high ionic
conductive non-protonic polar solvent, and a salt of a metal ion and the
feature of this invention is in the point of using the high molecular
compound having a phenyl group at the side chain, whereby even when the
organic solid electrolyte is impregnated with a large amount of a
nonprotonic polar solvent until the ionic conductivity becomes a practical
level, the film forming property is not astonishingly reduced and the
electrolyte shows a good film quality.
When a crosslinking agent is not used for the organic solid electrolyte of
this invention, the organic solid electrolyte is formed into a thin film
by dissolving the monomer and the salt of a metal ion in the non-protonic
polar solvent and heating the solution. Also, when a crosslinking agent is
used, after dissolving the monomer and the salt of a metal ion in the
nonprotonic polar solvent, a crosslinked high molecular matrix is formed
by heating the solution or a crosslinked high molecular matrix previously
formed is impregnated with the nonprotonic polar solvent and the salt of a
metal ion.
In other embodiment of this invention, the organic solid electrolyte of
this invention is composed of a porous film having a mean pore size of at
least 0.15 .mu.m filled with the high molecular compound, the high ionic
conductive nonprotonic polar solvent, and the salt of a metal ion. It has
been discovered that by using a porous film having a mean pore size of at
least 0.15 .mu.m, the interfacial resistance with an electrode material,
etc., is saturated at almost a definite value. Also, the porous film is
filled with the aforesaid components using a high molecular compound
having a phenyl group at the side chain as the high molecular compound,
even when the porous film is impregnated with the nonprotonic polar
solvent in such a large amount that the ionic conductivity becomes a
practical level, the porous film shows a good film quality without
reducing the film forming property of the high molecular compound.
When a crosslinking agent is not used as a high molecular compound, the
organic solid electrolyte is formed into a solid thin film by dissolving
the monomers and the salt of a metal ion in the nonprotonic polar solvent,
impregnating the porous film with the solution, and then heating the
porous film. Also, when a crosslinking agent is used as a high molecular
compound, a thin film of a crosslinked high molecular matrix is formed by
dissolving the monomers and the salt of a metal ion in the nonprotonic
polar solvent, impregnating the porous film with the solution, and then
heating the porous film, or a crosslinked high molecular matrix is
previously formed in the porous film and then the porous film is
impregnated with the nonprotonic polar solvent and the salt of a metal
ion.
As the porous film which is used in this invention, a film composed of a
polyolefin is used and a film composed of polyethylene or polypropylene is
preferably used. Also, the mean pore side (diameter) of the porous film is
at least 0.15 .mu.m but is preferably from 0.20 .mu.m to 5.0 .mu.m, and
more preferably from 0.30 .mu.m to 3.0 .mu.m.
If the mean pore size is small, the interfacial resistance with an
electrode material (Li, etc.) is reduced and as described above, if the
mean pore size of the porous film is less than 0.15 .mu.m, the reduction
extent of the interfacial resistance is greatly increased. Also, if the
mean pore size is too large, the film strength is undesirably reduced.
The porosity of the porous film is preferably from 10 to 90%, and more
preferably from 20 to 70%. If the porosity is too small, the impregnated
amount of the nonprotonic polar solvent becomes too small, the ionic
conductivity is reduced and also if the porosity is too large, the film
strength is reduced.
Furthermore, the film thickness is in the range of preferably from 5 to 500
.mu.m, and more preferably from 10 to 400 .mu.m. If the film thickness is
too thick, the resistance becomes large and if the film thickness is too
thin, the film strength is reduced.
Then, the aforesaid formulae (I) to (III) are described in detail.
In the aforesaid formulae, R.sub.1 represents a hydrogen atom, a lower
alkyl group, a cyano group, or a chlorine atom, preferably a hydrogen atom
or an alkyl group having from 1 to 3 carbon atoms, and more preferably a
hydrogen atom or a methyl group. R.sub.2 represents an alkyl group
(including methyl, ethyl, propyl, and butyl), an alkenyl group, an aryl
group, or an aralkyl group, preferably an alkyl group having from 1 to 5
carbon atoms, an alkenyl group having from 2 to 6 carbon atoms, an aryl
group having from 6 to 12 carbon atoms (e.g., a phenyl group), or an
aralky group having from 6 to 10 carbon atoms, and more preferably an
alkyl group having from 1 to 5 carbon atoms. When two or more R.sub.2
exist, R.sub.2 s may condense with each other, and preferably condense to
form an aromatic ring.
X represents --CO.sub.2 --,
##STR8##
--OCO--, or --O-- (wherein R.sub.3 represents a hydrogen atom or an alkyl
group including methyl, ethyl, propyl, and butyl).
X preferably represents --CO.sub.2 --,
##STR9##
--OCO--, or --O-- (wherein R.sub.3 represents a hydrogen atom or an alkyl
group having from 1 to 8 carbon atoms), and is more preferably --CO.sub.2
-- or
##STR10##
(wherein R.sub.3 represents a hydrogen atom or methyl, ethyl, propyl, and
butyl).
L represents an alkylene group, preferably an alkylene group having from 1
to 8 carbon atoms, and more preferably an alkylene group having from 1 to
5 carbon atoms.
In the above formulae, a represents 0 or 1 and m represents an integer of
from 0 to 5.
Y represents an l-valent atomic group composed of carbons or carbon and
hydrogen. When l is 2, Y represents a substituted or unsubstituted
alkylene group, a substituted or unsubstituted arylene group, or a
combination of these groups. When l is 2, preferred examples of Y are
##STR11##
When l is 3, Y represents the following formula (IV):
##STR12##
wherein A represents substituted or unsubstituted
##STR13##
(wherein R.sub.4 represents a hydrogen atom, a substituted or
unsubstituted C.sub.1-6 alkyl group, a substituted or unsubstituted
C.sub.2-6 alkenyl group, a substituted or unsubstituted C.sub.6-12 aryl
group, or a substituted or unsubstituted C.sub.7-14 aralkyl group);
L.sub.1, L.sub.2, and L.sub.3, which may be the same or different, have
the same meaning as those of Y when l is 2; and b, c, and d each
independently represents 0 or 1.
Preferred examples of Y when l=3 are
##STR14##
When l is 4, Y is represented by the following formula (V):
##STR15##
wherein B represents
##STR16##
substituted or unsubstituted
##STR17##
substituted or unsubstituted
##STR18##
or substituted or unsubstituted
##STR19##
L.sub.4, L.sub.5, L.sub.6 and L.sub.7, which may be the same or different,
have the same meaning as those of Y when l is 2; and e, f, g and h each
independently represents 0 or 1.
Preferred examples of Y when l is 4 are
##STR20##
When a crosslinking agent is not used, the high molecular compound for use
in this invention may contain a recurring unit induced from other monomer
component in addition to the recurring unit shown by formula (I) but in
this case, the recurring unit shown by formula (I) is contained in the
high molecular compound in an amount of at least 50 mol %, preferably at
least 70 mol %, and more preferably at least 80 mol %.
Also, in this case, the recurring unit shown by formula (I) may be used as
plural units.
Then, specific examples of the high molecular compound having the recurring
unit shown by formula (I) are illustrated below but the invention is not
limited to the compounds.
##STR21##
When a crosslinking agent is used, the high molecular matrix for use in
this invention may be formed using other monomer component in addition to
the monomer shown by formula (II) or formula (III). In this case, however,
the recurring unit induced from the monomer shown by formula (II) is
contained in the high molecular matrix in an amount of at least 50 mol %,
preferably at least 60 mol %, and more preferably at least 70 mol %. Also,
the recurring unit induced from the monomer shown by formula (III) is
contained in the high molecular matrix in an amount of from 0.1 to 50 mol
%, preferably from 0.2 to 40 mol %, and more preferably from 0.5 to 30 mol
%. Also, these recurring units may exist in the high molecular matrix as
plural units.
Then, specific examples of the monomer shown by formula (II) are
illustrated below but the invention is not limited to these compounds.
##STR22##
Then, specific examples of the monomer represented by formula (III) are
illustrated below but the invention is not limited to these compounds.
##STR23##
The high molecular compound or the crosslinked high molecular matrix for
use in this invention can be formed by heating and/or by the irradiation
of radiations but is preferably formed by heating corresponding
monomer(s).
In the case of causing the reaction by heating, it is preferred for
shortening the polymerization time to add from 0.01 to 5 mol % of a
thermal polymerization initiator to the system.
As the thermal polymerization initiator for use in this invention, there
are known thermal polymerization initiators such as azobis compounds,
peroxides, hydroperoxides, redox catalysts, etc., and specific examples
thereof are potassium persulfate, ammonium persulfate, t-butyl peroctoate,
benzoyl peroxide, isopropyl percarbonate, 2,4-dichlorobenzoyl peroxide,
methyl ethyl ketone peroxide, cumene hydroperoxide,
azobisisobutyronitrile, and 2,2'-azobis(2-amidinopropane) hydrochloride.
The heating temperature is preferably from 40.degree. to 160.degree. C.,
and more preferably from 50.degree. to 140.degree. C.
Also, the reaction of forming the high molecular compound may be performed
by the irradiation of radiation and as radiations which are used in this
case, ultraviolet rays, visible light, electron rays, and X-rays are
preferred.
In the case of causing the reaction by the irradiation of radiations, it is
preferred for quickly carrying out the reaction to add a radiation
sensitizer to the system. As the radiation sensitizer which can be used in
this invention, there are known sensitizers such as carbonyl compounds,
azobis compounds, peroxides, sulfur compounds, halogen compounds,
oxidation reduction series compounds, cation polymerization initiators,
benzophenone derivatives, benzanthrone derivatives, quinones, aromatic
nitro compounds, naphthothiazoline derivatives, benzothiazoline
derivatives, thioxanthones, naphthothiazole derivatives, ketocoumarin
compounds, benzothiazole derivatives, naphthofuranone compounds, pyrylium
salts, thiapyrylium salts, etc. Specific examples thereof are
N,N'-diethylaminobenzophenone, 1,2-benzanthraquinone, benzanthrone,
(3-methyl-1,3-diaza-1,9-benz)anthrone, picramide, 5-nitroacenaphthene,
2,6-dichloro-4-nitroaniline, p-nitroaniline, 2-chlorothioxanthone,
2-isopropylthioxanthone, dimethylthioxanthone, methylthioxanthone-1-ethyl
carboxylate, 2-nitrofluorene,
2-dibenzoylmethylene-3-methylnaphthothiazoline,
3,3-carbonyl-bis(7-diethylaminocoumarin), 2,4,6-triphenylthiapyrylium
perchlorate, 2-(p-chlorobenzoyl)naphthothiazole, erythrosine, Rose
Bengale, Eosine G, benzoin, 2-methylbenzoine,
trimethylsolylbenzoin-4-methoxybenzophenone, Michler's ketone, benzoin
methyl ether, acetophenone, and anthraquinone.
As a metal ion belonging to group Ia or group IIa of the Periodic Table,
which is used in this invention, there are ions of lithium, sodium, and
potassium and specific examples of the salt of the metal ion are
LiCF.sub.3 SO.sub.3, LiI, LiPF.sub.6, LiClO.sub.4, LiBF.sub.4,
LiAsF.sub.6, LiCF.sub.3 CO.sub.2, LiSCN, NaClO.sub.4, NaI, NaCFP.sub.3
SO.sub.3, NaBF.sub.4, NaAsF.sub.6, KCF.sub.3 SO.sub.3, KSCN, KPF.sub.6,
KClO.sub.4, and KAsF.sub.6. In the aforesaid salts, the Li salts are
preferred and they can be used singly or as a mixture of them.
The content of the salt of the metal ion to the nonprotonic solvent for use
in this invention may be less than the solubility thereof but is
preferably from about 0.1 to 8 mol/liter, and more preferably from 0.3 to
6 mol/liter. Also, the metal salt may be used as a mixture with other
electrolyte such as NBu.sub.4 FB.sub.4, etc.
As the nonprotonic polar solvent for use in this invention, it is
preferable to use at least one kind of solvent belonging to carbonates,
lactones, ethers (including cyclic ones), glycols, nitriles, esters, and
amides.
Preferred examples of carbonates are ethylene carbonate, propylene
carbonate, vinylene carbonate, ethyl carbonate, propyl carbonate,
4,5-dimethyl-1,3-dioxolan-2-one, 4-methoxymethyl-1,3-dioxolan-2-one, and
4,5-dimethoxymethyl-1,3-dioxolan-2-one.
Preferred examples of the lactones are .gamma.-butyrolactone,
.gamma.-valerolactone, .gamma.-caprylolactone, crotolactone,
.gamma.-caprolactone, .delta.-valerolactone,
##STR24##
Preferred examples of ethers are cyclic ethers such as tetrahydrofuran,
2-methyltetrahydrofuran, 3-methyltetrahydrofuran,
2,5-dimethyltetrahydrofuran, tetrahydropyran, 2-methyltetrahydropyran,
3-methyltetrahydropyran, dioxolan, 2-methyldioxolan, 4-methyldioxolan,
1,3-dioxane, 1,4-dioxane, 2-methyl-1,4-dioxane, etc., and chain ethers
such as diethyl ether, dipropyl ether, ethyl propyl ether,
1,2-dimethoxyethane, etc.
Preferred examples of glycols are diethylene glycol, dimethyl ether,
triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl
ether.
Preferred examples of nitriles are acetonitrile and propionitrile.
Preferred examples of esters are methyl formate and ethyl formate.
Preferred examples of amides are N,N-dimethylformamide and
N,N-dimethylacetamide.
Furthermore, nitromethane, thionyl chloride, sulforan, etc., can be
preferably used as the nonprotonic polar solvent.
The aforesaid non-protonic polar solvents can be used singly or as a
mixture thereof.
The high molecular compound or the crosslinked high molecular matrix is
impregnated with the aforesaid nonprotonic polar solvent in an amount of
preferably from 0.2 to 10 times (by weight), and more preferably from 0.5
to 5 times the amount of the compound or the matrix. If the impregnated
amount of the solvent is too small, the ionic conductivity becomes too low
and if the impregnated amount is too large, the problem of liquid leakage
happens.
When a crosslinking agent is not used in this invention, the organic solid
electrolyte of this invention is prepared by incorporating the nonprotonic
polar solvent and the salt of the metal ion in the high molecular compound
or the matrix at the polymerization thereof. Also, when a crosslinking
agent is used, the nonprotonic polar solvent and the salt of the metal ion
may be incorporated in a crosslinked high molecular matrix at the
formation thereof or after the formation thereof.
When the aforesaid components are incorporated in the crosslinked high
molecular matrix after the formation of the crosslinked high molecular
matrix, it is preferred that the high molecular matrix is impregnated with
the nonprotonic polar solution containing the salt of the metal ion or the
nonprotonic polar solution containing the salt of the metal ion is sprayed
onto or coated on the crosslinked high molecular matrix to incorporate the
solution therein.
Also, in this case, before incorporating the solution in the crosslinked
high molecular matrix, the high molecular matrix may be washed using the
nonprotonic polar solvent and as the washing method, the high molecular
matrix may be immersed in the solvent or a Soxhlet's washing method may be
employed.
Also, the organic solid electrolyte of this invention is used for a
secondary battery, as the positive electrode active material, oxides,
sulfides, and selenides of manganese, molybdenum, vanadium, titanium,
chromium, niobium, etc., active carbon (described in JP-A-60-167280),
carbon fibers (described in JP-A-61-10882), polyaniline, amino-substituted
aromatic polymers, heterocyclic polymers, polyacene, polyimine compounds,
etc., can be used. In these materials, active carbon, .gamma.-MnO.sub.2
(described in JP-A-62-108455 and JP-A-62-108457), a mixture of
.gamma.-.beta.-MnO.sub.2 and Li (described in U.S. Pat. No. 4,758,484),
amorphous V.sub.2 O.sub.5 (described in JP-A-61-200667), V.sub.6 O.sub.13,
MoS.sub.2 (described in JP-A-61-64083), TiS.sub.2 (described in
JP-A-62-222578), polyanilines (described in JP-A-60-65031, JP-A-60-149628,
JP-A-61-281128, JP-A-61-258831, JP-A-62-90878, JP-A-62-93868,
JP-A-62-119231, JP-A-62-181334, and JP-A-63-46223), polypyrrole (described
in West German Patents 3,307,954 Al, 3,318,857, 3,338,904, 3,420,854Al,
and 3,609,137Al, JP-A-60-152690, JP-A-62-72717, JP-A-62-93863, and
JP-A-62-143373), polyacene, polyacetylene (described in JP-A-57-121168,
JP-A-57-123659, JP-A-58-40781, JP-A-60-124370, JP-A-60-127669, and
JP-A-61-285678), and polyphenylene are particularly effective.
The electrode active material can usually contain an electrically
conductive material such as carbon, silver (described in JP-A-63-148554),
polyphenylene derivative (described in JP-A-59-20971), etc., and a
cementing material such as teflon, etc.
As a negative electrode active material, metal lithium, polyacetine,
polyacetylene, polyphenylene, lithium alloys with aluminum or magnesium
(described in JP-A-57-65670 and JP-A-57-98977), mercury alloys (described
in JP-A-58-111265), alloys with Pt, etc., (described in JP-A-60-79670),
Sn-Ni alloys (described in JP-A-6-86759), Wood's alloy (described in
JP-A-60-167279), alloys with conductive polymer (described in
JP-A-60-262351), Pd-Cd-Bi alloys (described in JP-A-61-29069), Ga-In
alloys (described in JP-A-61-66368), Pb-Mg alloys (described in
JP-A-61-66370), alloys with Zn, etc., (described in JP-A-61-68864), Al-Ag
alloys, etc., (described in JP-A-61-74258), Cd-Sn alloys, etc., (described
in JP-A-61-91864), Al-Ni alloys, etc., (described in JP-A-62-119865 and
JP-A-62-119866), Al-Mn alloys, etc., (described in U.S. Pat. No.
4,820,599), etc., can be used. In these materials, lithium metal or the Al
alloys of lithium are effectively used.
Then, the invention is described more practically by the following examples
but the invention is not limited to them.
EXAMPLE 1
Case of not using crosslinking agent
In 3 g of propylene carbonate (PC) were dissolved 1 g of benzyl
methacrylate and 0.4 g of LiBF.sub.4 and then 10 mg of
2,2'-azobis(methylisobutylate) was uniformly dissolved in the solution.
The solution was poured in a Teflon plate and polymerized by heating to
100.degree. C. for one hour in an argon gas atmosphere to provide thin
film (1) shown in Table 1 below.
By following the same procedure as above except that the components shown
in Table 1 were used in place of the aforesaid components, thin films (2)
to (12) shown in the same table were prepared.
COMPARATIVE EXAMPLE 1
Each of thin films (a) and (b) composed of PMMA, PC, and Li salts described
in JP-B-57-9671 was prepared by the manner of heating the PC solution of
PMMA.
COMPARATIVE EXAMPLE 2
Each of thin films (c) and (d) composed of poly(1-vinyl-1,2-propanediol
cyclic carbonate) (E-1) having a mean molecular weight of 10,000, PC and
Li salts described in JP-A-62-22375 was prepared by the manner of heating
the PC solution of the aforesaid polymer.
Using each of the thin films thus obtained, a sample composed of Li/thin
film/Li was prepared, the impedance thereof was measured at 0.1 to 10 KHz,
and from the Cole-Cole's plots, the ionic conductivity was determined.
In addition, the film strength was measured by the following method.
Each thin film was cut into a disk having a diameter of 1.7 cm, the disk
was placed on a stainless steel plate, a stainless steel plate having the
same diameter as that of the disk was placed on the disk, a weight was
applied to them from above, and the weight at which the thin film was
clearly protruded was employed as the film strength.
The evaluation results are shown in Table 1 below.
TABLE 1
__________________________________________________________________________
Polymer Nonprotonic
x of Metal Ion Salt/Non-
Polar Ion Film
Formula
protonic Polar Solvent
Solvent/Polymer
Conductivity
Strength
No. (I) (concentration M)
(weight ratio)
(s/cm) (kg/cm.sup.2)
__________________________________________________________________________
(1)
P-2 LiBF.sub.4 /PC (1.3 M)
2.5 8.5 .times. 10.sup.-4
75
(2)
P-2 LiClO.sub.4 /.gamma.-BL (2M)
2.0 7.0 .times. 10.sup.-4
80
(3)
P-1 LiBF.sub.4 /PC + EC*.sup.1 (1/1) (2 M)
1.4 5.1 .times. 10.sup.-4
>100
(4)
P-3 LiCF.sub.3 SO.sub.3 /DEDM*.sup.2 (1 M)
2.2 3.8 .times. 10.sup.-4
85
(5)
P-5 LiPF.sub.6 /PC + EC (2M)
1.3 7.2 .times. 10.sup.-4
>100
(6)*.sup.3
P-7 LiBF.sub.4 /PC (1.5 M)
2.0 7.9 .times. 10.sup.-4
45
(7) P-5 LiCF.sub.3 SO.sub.3 /.gamma.-BL (1.2 M)
1.8 6.5 .times. 10.sup.-4
70
(8)
P-12 LiCF.sub.3 SO.sub.3 /PC + EC (3 M)
2.0 1.5 .times. 10.sup. -3
55
(9)
BL (1.5 M)iBF.sub.4 /PC + .gamma.
2.1 8.0 .times. 10.sup.-4
>100
(10)
P-4 LiClO.sub.4 /PC + EC (1.5 M)
1.2 4.4 .times. 10.sup.-4
"
(11)
P-6 LiBF.sub.4 /PC + DEDM (1 M)
1.8 9.5 .times. 10.sup.-4
"
(12)*.sup.3
P-10 LiBF.sub.4 /PC (1.5 M)
2.0 7.1 .times. 10.sup.-4
55
(a) PMMA LiClO.sub.4 /PC (1 M)
2.5 7.0 .times. 10.sup.-4
<10
(b) " LiBF.sub.4 /butyl acetate (1 M)
0.8 6.7 .times. 10.sup.-5
30
(c) (E-1)
LiBPh.sub.4 /PC (1.5 M)
2.0 5.1 .times. 10.sup.-4
<10
(d) " " 1.0 1.1 .times. 10.sup.-4
20
__________________________________________________________________________
In Table 1:
*.sup.1 Ethylene carbonate
*.sup.2 Diethylene glycol dimethyl ether
*.sup.3 Polymerized without using a polymerization initiator
As is clear from the results shown in Table 1, it can be seen that thin
films (1) to (12) in the examples of this invention are excellent in the
ionic conductivity and/or the film strength as compared to thin films (a)
to (d) in the comparative examples.
EXAMPLE 2
Case of using crosslinking agent
In 3 g of propylene carbonate (PC) were dissolved 0.9 g of Monomer M-2, 0.1
g of Monomer C-2, and 0.4 g of LiBF.sub.4 and then 10 mg of benzoyl
peroxide was uniformly dissolved in the solution.
The solution was poured in a Teflon plate and polymerized by heating to
120.degree. C. for one hour under an argon gas atmosphere to provide thin
film (13) shown in Table 2.
By following the aforesaid method of incorporating each nonprotonic polar
solvent and each Li salt into each matrix at the reaction by heating using
the components shown in Table 2, thin films (14) to (24) were obtained.
COMPARATIVE EXAMPLE 3
Thin films (e) and (f) composed of Polymer (E-2) shown below, PC, and Li
salts described in U.S. Pat. No. 4,822,701 were prepared.
##STR25##
On each of the thin films thus obtained, the ionic conductivity and the
film strength were evaluated by the same manners as in Example 1.
The results obtained are shown in Table 2.
TABLE 2
__________________________________________________________________________
Monomer
Monomer Nonprotonic
x of y of x/y Metal Ion Salt/Non-
Polar Ionic Film
Formula
Formula
(weight
protonic Polar Solvent
Solvent/Polymer
Conductivity
Strength
No. (II) (III) ratio)
(concentration M)
(weight ratio)
(s/cm) (kg/cm.sup.2)
__________________________________________________________________________
(13)
M-2 C-2 90/10
LiBF.sub.4 /PC (1.3 M)
2.3 7.5 .times. 10.sup.-4
95
(14)
M-2 C-5 95/5 LiClO.sub.4 /.gamma.-BL (2 M)
2.0 6.9 .times. 10.sup.-4
80
(15)
M-1 C-1 85/15
LiBF.sub.4 /PC + EC (1/1) (2 M)
2.0 8.1 .times. 10.sup.-4
>100
(16)
M-3 C-8 90/10
LiCF.sub.3 SO.sub.3 /DEDM (1 M)
2.2 4.2 .times. 10.sup.-4
"
(17)
M-5 C-6 90/10
LiPF.sub.6 /PC + EC (2 M)
2.4 7.1 .times. 10.sup.-4
"
(18)*.sup.4
M-7 C-2 90/10
LiBF.sub.4 /PC (1.5 M)
2.0 6.6 .times. 10.sup.-4
55
(19)
M-2 + M-5
C-10 95/5 LiCF.sub.3 SO.sub.3 /.gamma.-BL (1.2
2.5 5.6 .times.
>100 p.-4
(1/1)
(20)
M-2 + M-12
C-11 90/10
LiCF.sub.3 SO.sub.3 /PC + EC (3 M)
2.0 1.0 .times. 10.sup.-3
"
(2/1)
(21)
BL (1.5 M) C-3 95/5 LiBF.sub.4 /PC + .gamma.
1.9 7.7 .times. 10.sup.-4
"
(22)
M-4 C-8 95/5 LiClO.sub.4 /PC + EC (1.5 M)
2.5 4.5 .times. 10.sup.-4
"
(23)
M-6 C-8 92/8 LiBF.sub.4 /PC + DEDM (1 M)
1.8 5.2 .times. 10.sup.-4
"
(24)*.sup.4
M-10 C-9 95/5 LiBF.sub.4 /PC (1.5 M)
2.0 8.4 .times. 10.sup.-4
70
(e) E-2 -- -- LiClO.sub.4 /PC (1.2 M)
1.0 1.5 .times. 10.sup.-4
25
(f) E-2 -- -- LiClO.sub.4 /PC (1.2 M)
2.0 5.2 .times. 10.sup.-4
<10
__________________________________________________________________________
In Table 2:
*.sup.4 Polymerized without using a polymerization initiator.
As is clear from the results shown in Table 2, it can be seen that thin
films (13) to (24) in the examples of this invention are remarkably
excellent in the ionic conductivity and the film strength as compared to
thin films (e) and (f) in the comparative examples.
EXAMPLE 3
Case of using crosslinking agent
In 3 g of PC were dissolved 0.8 g of Monomer M-2 and 0.2 g of Monomer C-1
and then 0.1 g of azobisisobutyronitrile was uniformly dissolved in the
solution.
The solution was poured in a Teflon plate and gelled by heating the
solution to 125.degree. C. for one hour to provide a thin film. The thin
film was immersed in a PC solution (concentration of 1.4M) for one hour
and the immersion operation was further repeated once to provide thin film
(25) shown in Table 3. By following the aforesaid procedure using the
components shown in Table 3, thin films (26) to (36) were further
prepared.
COMPARATIVE EXAMPLE 4
Thin films (g) and (h) composed of Polymer (E-3) shown below, low molecular
weight PEO, and Li salts described in JP-A-63-135477 were prepared by heat
polymerization.
##STR26##
COMPARATIVE EXAMPLE 5
Thin films (i) and (j) composed Polymer (E-4) shown below, PC or
tetragraim, Li salts, and high molecular weight PEO described in U.S. Pat.
No. 4,830,939 were prepared by radiation polymerization.
##STR27##
On each of the thin films thus prepared, the ionic conductivity and the
film strength were evaluated by the same manners as in Example 1.
The results obtained are shown in Table 3.
TABLE 3
__________________________________________________________________________
Monomer
Monomer Nonprotonic
x of y of x/y Metal Ion Salt/Non-
Polar Solvent/
Ionic Film
Formula
Formula (weight
protonic Polar Solvent
Polymer Conductivity
Strength
No. (II) (III) ratio)
(concentration M) (weight ratio)
(s/cm) (kg/cm.sup.2)
__________________________________________________________________________
(25)
M-2 C-1 90/10
LiBF.sub.4 /PC (1.4 M)
2.6 7.3 .times. 10.sup.-4
90
(26)
M-1 C-10 95/5 LiBF.sub.4 /PC + 3MeTHF*.sup.5
2.11) 9.1 .times. 10.sup.-4
85
(1.5 M)
(27)
M-3 C-1 + C-9 (1/1)
90/10
LiCF.sub.3 SO.sub.3 /EC + THF*.sup.6
1.81) 1.0 .times. 10.sup.-3
>100
(1.2 M)
(28)
M-10 C-8 95/5 LiCF.sub.3 SO.sub.3 /PC + DME*.sup.7
2.01) 1.7 .times. 10.sup.-3
"
(2 M)
(29)
M-2 C-8 90/10
LiClO.sub.4 /PC + EC (1/1) (2 M)
2.7 7.8 .times. 10.sup.-4
"
(30)
M-7 C-6 98/2 LiClO.sub.4 /PC + DMF*.sup.8 (5/1)
2.5 1.2 .times. 10.sup.-3
"
(1.2 M)
(31)
M-1 + M-4
C-12 95/5 LiBF.sub.4 /.gamma.-BL (1.2 M)
2.8 5.4 .times. 10.sup.-4
95
(1/1)
(32)
M-2 + M-12
C-9 85/15
LiCF.sub.3 SO.sub.3 /DME (1.0 M)
1.6 8.9 .times. 10.sup.-4
>100
(33)
M-2 + M-13
C-9 97/3 LiBF.sub.4 /PC + DME (1/1) (1.4
2.0 1.8 .times. 10.sup.-3
"
(34)
M-1 C-3 90/10
LiPF.sub.6 /EC + 3MeTHP*.sup.9 (3/1) (2
2.0 7.0 .times. 10.sup.-4
>100
(35)
M-2 C-5 92/8 LiCF.sub.3 SO.sub.3 /.gamma.-BL (1.5
2.0 7.4 .times. 10.sup.-4
"
(36)
M-11 C-8 97/3 LiCLO.sub.4 /sulforan + DME (3/1)
2.3 9.1 .times. 10.sup.-4
"
(1 M)
(g) E-3 -- -- LiClO.sub.4 /PEO400 (0.8 M)
0.8 7.2 .times. 10.sup.-5
45
(h) E-3 -- -- LiClO.sub.4 /PEO300 (1 M)
1.5 2.1 .times. 10.sup.-4
20
(i) E-4/PEO
-- -- LiCF.sub.3 SO.sub.3 /PC (2 M)
5.0 1.0 .times. 10.sup.-3
<10
500,000
(j) E-4/PEO
-- -- LiCF.sub.3 SO.sub.3 /tetragraim (2
5.0 2.1 .times. 10.sup.-4
<10
500,000
__________________________________________________________________________
*.sup.5 3Methyltetrahydrofuran
*.sup.6 Tetrahydrofuran
*.sup.7 1,2Dimethoxyethane
*.sup.8 N,NDimethylformamide
*.sup.9 3Methyltetrahydropyran
As is clear from the results in Table 3, it can be seen that thin films
(25) to (36) in the examples of this invention are excellent in the ionic
conductivity and the film strength as compared to thin films (g), (h), and
(j) in the comparative examples and are remarkably excellent in the film
strength as compared to thin film (i) in the comparative example.
EXAMPLE 4
Case of not using crosslinking agent
In 3 g of PC were dissolved 1 g of benzyl methacrylate and 0.4 g of
LiBF.sub.4 and then 10 mg of 2,2'-azobis(methylene isobutyrate) was
uniformly dissolved in the solution. A porous polypropylene film (having a
diameter of 1.7 cm, a thickness of 200 .mu.m, a mean pore size of 1.2
.mu.m, and a porosity of 45%) was impregnated with 100 .mu.l of the
aforesaid solution. Then, the solution was polymerized by heating to
100.degree. C. for one hour under an argon gas atmosphere to provide thin
film (1') shown in Table 4 below.
By following the same procedure as above using the components shown in
Table 4, thin films (2') to (12') were obtained.
COMPARATIVE EXAMPLE 6
Thin films (a') and (b') composed of PMMA, PC, and Li salts described in
JP-B-57-9671 were prepared by the method of heating the PC solution of
PMMA.
COMPARATIVE EXAMPLE 7
Thin films (c') and (d') composed of poly(1-vinyl-1,2-propanediol cyclic
carbonate) (E-1) having a mean molecular weight of 10,000, PC, and Li
salts described in JP-A-62-22375 by the method of heating the PC solution
of the polymer.
Using each of the thin films, a sample composed of Li/thin film/Li was
prepared, the impedance thereof was measured at 0.1 to 10 KHz, from the
Cole-Cole's plots, the ionic conductivity and the interfacial resistance
were determined.
Also, each of the thin films was cut into a disk having a diameter of 1.7
cm, the disk was placed on a stainless steel plate, a stainless plate
having the same diameter as that of the disk was placed on the disk, a
weight was applied to them from above, and the extruded weight of the thin
film was employed as the film strength. The evaluated results are shown in
Table 4 below.
TABLE 4
__________________________________________________________________________
Polymer Nonprotonic Porous Film
x of Metal Ion Salt/Non-
Polar Mean Pore
Formula
protonic Polar Solvent
Solvent/Polymer
Thickness
Size Porosity
No. (I) (concentration M)
(weight ratio)
Material
(.mu.m)
(.mu.m)
(%)
__________________________________________________________________________
(1')
P-2 LiBF.sub.4 /PC (1.3 M)
2.5 PP*.sup.4
140 0.80 45
(2')
P-2 LiClO.sub.4 /.gamma.-BL (2 M)
2.0 " " " "
(3')
P-1 LiBF.sub.4 /PC + EC*.sup.1 (1/1) (2 M)
1.4 " " " "
(4')
P-3 LiCF.sub.3 SO.sub.3 /DEDM*.sup.2 (1 M)
2.2 " 75 0.35 40
(5')
P-5 LiPF.sub.6 /PC + EC (1/1) (2 M)
1.3 " " " "
(6')*.sup.3
P-7 LiBF.sub.4 /PF (1.5 M)
2.0 " " " "
(7')
P-5 LiCF.sub.3 SO.sub.3 /.gamma.-BL (1.2 M)
1.8 " 80 0.15 48
(8')
P-12 LiCF.sub.3 SO.sub.3 /PC + EC (3 M)
2.0 " " " "
(9')
BL (2/1) (1.5 M)b.4 /PC + .gamma.
1.2 PE*.sup.5 155 0.75 38
(10')
P-4 LiCLO.sub.4 /PC + EC (2/1) (1.5 M)
1.2 " " " "
(11')
P-6 LiBF.sub.4 /PC + DEDM (3/1) (1 M)
1.8 " 70 0.45 36
(12')
P-10 LiBF.sub.4 /PC (1.5 M)
2.0 " " " "
(a')
PMMA LiClO.sub.4 /PC (1 M)
2.5 PP 140 0.8 45
(b')
" LiBF.sub.4 /butyl acetate (1 M)
0.8 " " " "
(c')
(E-1)
LiBPh.sub.4 /PC (1.5 M)
2.0 PP 140 0.8 45
(d')
" " 1.0 " " " "
__________________________________________________________________________
*.sup.1 Ethylene carbonate
*.sup.2 Diethylene glycol dimethyl ether
*.sup.3 Polymerized without using polymerization initiator
*.sup.4 Polypropylene
*.sup.5 Polyethylene
TABLE 4'
______________________________________
Ionic Interfacial
Conductivity Resistance
Film Strength
No. (s/cm) (.OMEGA./cm)
(kg/cm.sup.2)
______________________________________
(1') 8.0 .times. 10.sup.-4
21 85
(2') 7.0 .times. 10.sup.-4
19 80
(3') 4.9 .times. 10.sup.-4
20 >100
(4') 4.5 .times. 10.sup.-4
27 90
(5') 7.1 .times. 10.sup.-4
25 >100
(6') 6.9 .times. 10.sup.-4
24 75
(7') 5.8 .times. 10.sup.-4
31 >100
(8') 1.1 .times. 10.sup.-3
33 "
(9') 7.3 .times. 10.sup.-4
24 "
(10') 4.9 .times. 10.sup.-4
19 "
(11') 8.7 .times. 10.sup.-4
20 "
(12') 6.2 .times. 10.sup.-4
21 90
(a') 7.0 .times. 10.sup.-4
27 25
(b') 8.5 .times. 10.sup.-5
38 55
(c') 4.5 .times. 10.sup.-4
26 20
(d') 1.0 .times. 10.sup.-4
20 50
______________________________________
As is clear from the results shown in Table 4, thin films (a') to (d') in
the comparative examples each uses a porous film having large pore sizes
but since the high molecular compounds used are greatly inferior in film
forming property, when the impregnated amount of the nonprotonic polar
solvent is increased for increasing the ionic conductivity, the film
strength of the thin film is greatly reduced. Thus, in the comparative
samples, it is impossible to increase both the ionic conductivity and the
film forming property (film strength).
On the other hand, in thin films (1') to (12') in the examples of this
invention, in spite of using a porous film having large pore sizes, all
the high ionic conductivity, the low interfacial resistance, and the high
film forming property can be satisfied by combining with the high
molecular compound having the specific structure.
That is, it is clear that the thin films obtained in Example 4 are
excellent as compared to the thin films in Comparative Example 6 and 7.
EXAMPLE 5
Case of using crosslinking agent
In 3 g of PC were dissolved 0.9 g of Monomer M-2, 0.1 g of Monomer C-2, and
0.4 g of LiBF4 and then 10 ml of benzoyl peroxide was uniformly dissolved
in the solution. Then, a porous polypropylene film (having a diameter of
1.7 cm, a thickness of 200 .mu.m, a mean pore size of 1.2 .mu.m, and a
porosity of 45%) was impregnated with 100 .mu.l of the solution and the
solution was polymerized by heating to 110.degree. C. for one hour under
an argon gas atmosphere to provide thin film (13') shown in Table 5.
Also, by following the same procedure as above using the components shown
in Table 5, thin films (14') to (24') were prepared.
COMPARATIVE EXAMPLE 8
Thin films (e') and (f') were prepared by impregnating porous polyethylene
films each having a mean pore size of 0.085 .mu.m and a mean pore size of
0.10 .mu.m with a solution of LiClO.sub.4 dissolved in tetraethylene
glycol dimethyl ether as described in U.S. Pat. No. 4,849,311.
COMPARATIVE EXAMPLE 9
Thin films (g') and (h') composed of Polymer (E-2) shown in Comparative
Example 3, PC, and the Li salts described in U S. Pat. No. 4,822,701 were
prepared.
On each of the thin films thus obtained, the ionic conductivity, the
interfacial resistance, and the film forming property (film strength) were
evaluated by the same manners as in Example 4.
The results obtained are shown in Table 5, below.
TABLE 5
__________________________________________________________________________
Nonprotonic
Polar Porous Film
Monomer Monomer Solvent/ Mean
x of y of x/y Metal Ion Salt/Non-
Polymer Thick-
Pore
Por-
Formula Formula
(weight
protonic Polar Solvent
(weight
Ma-
ness
Size
osity
No. (II) (III) ratio)
(concentration M)
ratio) terial
(.mu.m)
(.mu.m)
(%)
__________________________________________________________________________
(13')
M-2 C-2 90/10
LiBF.sub.4 PC (1.3 M)
2.3 PP 80 0.15
48
(14')
" C-5 95/5 LiClO.sub.4 /.gamma.-BL (2 M)
2.0 " " " "
(15')
M-1 C-1 85/15
LiBF.sub.4 /PC + EC (1/1) (2 M)
2.0 " 75 0.35
40
(16')
M-3 C-8 90/10
LiCF.sub.3 SO.sub.3 /DEDM (1 M)
2.2 " " " "
(17')
M-5 C-6 " LiPF.sub.6 /PC + EC (1/1) (2 M)
2.4 PE 155 0.75
38
(18')*.sup.6
M-7 C-2 " LiBF.sub. 4 /PC (1.5 M)
2.0 " 70 0.45
"
(19')
M-2 + M-5 (1/1)
C-10 95/5 LiCF.sub.3 SO.sub.3 /.gamma.-BL (1.2
2.5 " " " 36
(20')
M-2 + M-12 (2/1)
C-11 90/10
LiCF.sub.3 SO.sub.3 /PC + EC (2/1) (3
2.0 PP 140 0.8 45
(21')
BL (2/1) (1.5 M)3 95/5 LiBF.sub.4 /PC + .gamma.
1.9 " " " "
(22')
M-4 C-8 " LiClO.sub.4 /PC + EC (1/1) (1.5
2.5 " 80 0.15
48
(23')
M-6 " 92/8 LiBF.sub.4 /PC + DEDM (3/1) (1
1.8 " " " "
(24')*.sup.6
M-10 C-9 95/5 LiBF.sub.4 /PC (1.5 M)
2.0 " 75 0.35
40
(e')
-- -- -- LiClO.sub.4 /TEG*.sup.7 (1 M)
-- PE 25 0.04
42
(f')
-- -- -- LiClO.sub.4 /TEG*.sup.7 (1.5 M)
-- " 30 0.10
38
(g')
E-2 -- -- LiClO.sub.4 /PC (1.2 M)
1.0 -- -- -- --
(h')
" -- -- " 2.0 -- -- -- --
__________________________________________________________________________
*.sup.6 Polymerized without using polymerization initiator
*.sup.7 Tetraethylene glycol dimethyl ether
TABLE 5'
______________________________________
Ionic Interfacial
Conductivity Resistance
Film Strength
No. (s/cm) (.OMEGA./cm)
(kg/cm.sup.2)
______________________________________
(13') 8.2 .times. 10.sup.-4
29 >100
(14') 5.8 .times. 10.sup.-4
34 "
(15') 7.2 .times. 10.sup.-4
24 "
(16') 4.3 .times. 10.sup.-4
20 "
(17') 6.7 .times. 10.sup.-4
18 90
(18') 7.2 .times. 10.sup.-4
22 85
(18') 4.4 .times. 10.sup.-4
23 >100
(20') 9.5 .times. 10.sup.-4
19 80
(21') 7.7 .times. 10.sup.-4
19 95
(22') 5.4 .times. 10.sup.-4
30 >100
(23') 6.2 .times. 10.sup.-4
31 "
(24') 8.8 .times. 10.sup.-4
24 "
(e') 5.9 .times. 10.sup.-5
110 "
(f') 7.2 .times. 10.sup.-5
58 "
(g') 1.5 .times. 10.sup.-4
30 25
(h') 5.2 .times. 10.sup.-4
28 <10
______________________________________
As is clear from the results shown in Table 5', in thin films (g') and (h')
in the comparative example, the polymeric film is impregnated with a large
amount of the nonprotonic polar solvent for increasing the ionic
conductivity, whereby the film strength is greatly reduced. However, in
thin films (13') to (24') in the examples of this invention, all the high
ionic conductivity, the low interfacial resistance, and the high film
forming property can be satisfied, as well as Example 4. On the other
hand, in thin films (e') and (f') in the comparative example, since a
porous film having small pore sizes is used, the film strength is high but
the interfacial resistance with Li is very large and also the ionic
conductivity is low.
That is, the thin films in Example 5 are clearly excellent in comparison to
the thin films in Comparative Examples 8 and 9.
EXAMPLE 6
Case of using crosslinking agent
In 3 g of PC were dissolved 0.8 g of Monomer-2 and 0.2 g of Monomer C-1 and
then 0.1 g of azobisisobutyronitrile was uniformly dissolved in the
solution.
Then, a porous polypropylene film (diameter of 1.7 cm, a thickness of 200
.mu.m, a mean pore size of 1.2 .mu.m, and a porosity of 45%) was
impregnated with 100 .mu.l of the aforesaid solution and the solution was
polymerized by heating to 110.degree. C. for one hour under an argon gas
atmosphere to provide a porous film filled with a crosslinked high
molecular matrix. The thin film was immersed in a PC solution of
LiBF.sub.4 (concentration of 1.4M) for one hour and further the immersion
operation was further repeated once to provide thin film (25') shown in
Table 6.
By following the same procedure by the method of impregnating with the
nonprotonic polar solvent after reaction by heating, thin films (26') to
(36') were prepared.
COMPARATIVE EXAMPLE 10
Thin films (i') and (j') composed of Polymer (E-3) shown in Comparative
Example 4, low molecular weight PEO, and Li salts described in
JP-A-63-135477 were prepared by heat polymerization.
COMPARATIVE EXAMPLE 11
Thin films (k') and (l') composed of Polymer (E-4) shown in Comparative
Example 5, PC or tetragram, Li salts and high molecular weight PEO
described in U.S. Pat. No. 4,830,939 were prepared.
On each of the thin films thus obtained, the ionic conductivity, the
interfacial resistance, and the film forming property (film strength) were
evaluated as in Example 4.
The results are shown in Table 6'.
TABLE 6
__________________________________________________________________________
Nonprotonic
Polar Porous Film
Monomer Monomer Solvent/ Mean
x of y of x/y Metal Ion Salt/Non-
Polymer Thick-
Pore
Por-
Formula Formula (weight
protonic Polar Solvent
(weight
Ma-
ness
Size
osity
No. (II) (III) ratio)
(concentration M)
ratio) terial
(.mu.m)
(.mu.m)
(%)
__________________________________________________________________________
(25')
M-2 C-1 90/10
LiBF.sub.4 PC (1.4 M)
2.6 PP 140 0.8 45
(26')
M-1 C-10 95/5 LiBF.sub.4 /PC + 3MeTHF*.sup.8
2.1 " " " "
(3/1) (1.5 M)
(27')
M-3 C-1 + C-9 (1/1)
90/10
LiCF.sub.3 SO.sub.3 /EC + THF*.sup.9
1.8 " 80 0.15
48
(1.2 M)
(28')
M-10 C-8 95/5 LiCF.sub.3 SO.sub.3 /PC + DME*.sup.10
2.0 " " " "
(2 M)
(29')
M-2 " 90/10
LiClO.sub.4 /PC + EC
2.7 " 75 0.35
40
(1/1) (2 M)
(30')
M-7 C-6 98/2 LiClO.sub.4 /PC + DMF*.sup.11
2.5 " " " "
(5/1) (1.2 M)
(31')
M-1 + M-4 (1/1)
C-12 95/5 LiBF.sub.4 /.gamma.-BL (1.2
2.8 PE 155 0.75
38
(32')
M-2 + M-12 (1/1)
C-9 85/15
LiCF.sub.3 SO.sub.3 /DME (1.0
1.6 " " " "
(33')
M-2 + M-13 (3/1)
" 97/3 LiBF.sub.4 /PC + DME
2.0 " 70 0.45
36
(2/1) (1.4 M)
(34')
M-1 C-3 90/10
LiPF.sub.6 /EC + 3MeTHP*.sup.12
2.0 " " " "
(3/1) (2 M)
(35')
M-2 C-5 92/8 LiCF.sub.3 SO.sub.3 /.gamma.-BL (1.5
2.0 PE 75 0.35
40
(36')
M-11 C-8 97/3 LiClO.sub.3 /sulforan + DME
2.3 " " " "
(3/1) (1 M)
(i')
E-3 -- -- LiClO.sub.4 /PEO 400 (0.8 M)
0.8 -- -- -- --
(j')
" -- -- LiClO.sub.4 /PEO 300 (1 M)
1.5 -- -- -- --
(k')
E-4/PEO -- -- LiCF.sub.3 SO.sub.3 /PC (2 M)
3.0 -- -- -- --
(l')
" -- -- LiCF.sub.3 SO.sub.3 /tetragraim (2
3.0 -- -- -- --
__________________________________________________________________________
*.sup.8 3Methyltetrahydrofuran
*.sup.9 Tetrahydrofuran
*.sup.10 Dimethoxyethane
*.sup.11 N,NDimethylforamide
*.sup.12 Tetrahydropyran
TABLE 6'
______________________________________
Ionic Interfacial
Conductivity Resistance
Film Strength
No. (s/cm) (.OMEGA./cm)
(kg/cm.sup.2)
______________________________________
(25') 7.5 .times. 10.sup.-4
19 85
(26') 9.5 .times. 10.sup.-4
17 >100
(27') 1.1 .times. 10.sup.-3
28 "
(28') 1.5 .times. 10.sup.-3
29 "
(29') 8.7 .times. 10.sup.-4
25 "
(30') 1.2 .times. 10.sup.-3
20 "
(31') 5.4 .times. 10.sup.-4
23 80
(32') 8.9 .times. 10.sup.-4
19 95
(33') 1.6 .times. 10.sup.-3
22 >100
(34') 7.0 .times. 10.sup.-4
20 "
(35') 7.4 .times. 10.sup.-4
21 "
(36') 9.7 .times. 10.sup.-4
18 "
(i') 7.2 .times. 10.sup.-5
48 45
(j') 1.1 .times. 10.sup.-4
40 20
(k') 1.0 .times. 10.sup.-3
22 <10
(1') 2.1 .times. 10.sup. -4
35 "
______________________________________
As is clear from the results shown in Table 6', it can be seen that thin
layers (25') to (36') in Example 6 of this invention satisfied all the
properties of the high ionic conductivity, the low interfacial resistance,
and the high film forming property (film strength) as in Example 4. On the
other hand, in thin films (i') and (j') in the comparative example, the
ionic conductivity is low since the low molecular weight polyethylene
glycol is used as the ionic conductor and also the film strength is
greatly reduced if a large amount of the ionic conductor is impregnated
for increasing the ionic conductivity.
Furthermore, in thin films (k') and (l') in the comparative example, when a
large amount of the nonprotonic polar solvent is impregnated for
increasing the ionic conductivity, the film strength is greatly reduced.
Thus, it can be clearly seen that the thin films in Example 6 are excellent
as compared with samples in Comparative Examples 10 and 11.
As described above, the thin films in Examples 4 to 6 are excellent in
either or all of the ionic conductivity, the interfacial resistance, and
the film thickness as compared to the thin films in Comparative Examples 6
to 11.
Then, examples of the cases of applying each of the organic solid
electrolytes of this invention to a Li secondary battery are explained.
EXAMPLE 7
Using each of the organic solid electrolytes prepared in Examples 1 to 3
(or in Examples 4 to 6), a battery (cell) shown in FIG. 1 was prepared. In
this case, as the positive electrode active material, a positive electrode
pellet (having a diameter of 15 mm and a capacity of 20 mAH) composed of
V.sub.6 O.sub.13 described in Denki Kagaku (Electrochemistry), Vol. 54,
691 (1986) was used, as a negative electrode active material, a metal
lithium (having a diameter of 15 mm and a capacity of 40 mAH) was used,
and organic solid electrode (1) (having a diameter of 17 mm) prepared in
Example 1 was used between the positive electrode pellet and the negative
electrode pellet. On the lithium battery, charging and discharging tests
were carried out in the ranges of an electric current density of 1.1
mA/cm.sup.2 and a voltage of 3.1 V to 1.7 V. The results are shown as
Curve (a) in FIG. 2 as the change of the charging and discharging
capacity.
By following the same procedure as above using the components shown in
Table 7, lithium batteries (b) to (g) were prepared and the charging and
discharging tests were carried out.
Nos. (a) to (d) shown in Table 7 correspond to curves (a) to (d) shown in
FIG. 2 and Nos. (e) to (g) shown in Table 7 correspond to curves (e) to
(g) of FIG. 3.
COMPARATIVE EXAMPLE 12
Using each of the solid electrolytes prepared in Comparative Examples 1 and
2 (or Comparative Examples 6 and 7), each of lithium batteries (p) and (q)
shown in Table 7 were prepared by the same manner as in Example 7 and the
charging and discharging tests were carried out on each battery. The test
results of using the solid electrolytes prepared in Comparative Examples 1
and 2 are shown as curves (p) and (q) in FIG. 2 and the results of using
the solid electrolytes in Comparative Examples 1 and 2 are shown as curves
(p) and (q) in FIG. 3.
As is clear from the results shown in FIG. 2 and FIG. 3, it can be seen
that the batteries using the organic solid electrolytes of this invention
are excellent in the change of discharging capacity as compared to the
batteries using the solid electrolytes in Comparative Examples 1 and 2 (or
the solid electrodes in Comparative Examples 6 and 7).
(The same results were obtained using the organic solid electrolytes
prepared in Examples 4 to 6 and Comparative Examples 6 and 7.)
TABLE 7
__________________________________________________________________________
Negative Electrode
Positive Electrode Active
Active Material Current
Changing and
Material (15 mm.phi.,
(15 mm.phi.,
Electrolyte
Density
Discharging
No.
capacity, 20 mAH)
capacity, 40 mAH)
(17 mm.phi.)
(mA/cm.sup.2)
Depth
__________________________________________________________________________
(a)
Pellet composed of V.sub.6 O.sub.13 *.sup.1
Metal (1) of
1.1 3.1V-1.7V
Lithium Example 1
(b)
Pellet composed of .gamma.-.beta.-
Metal (25) of
" 3.3V-1.9V
MnO.sub.2 + Li.sub.2 MnO.sub.3 *.sup.2
Lithium Example 3
(c)
Pellet composed of
Metal (13) of
" 3.0V-2.0V
polyaniline*.sup.3
Lithium Example 2
(d)
Pellet composed of
Li--Al Alloy
(20) of
" 3.3V-1.7V
polypyrrole*.sup.4 Example 2
(e)
Pellet composed of
" (28) of
" 3.2V -1.8V
amorphous V.sub.2 O.sub.5 *.sup.5
Example 3
(f)
Pellet composed of
" (33) of
" 3.0V-2.0V
polyaniline*.sup.6 Example 3
(g)
Pellet composed of
Metal (8) of
" 3.3V-1.7V
polypyrrole*.sup.7
Lithium Example 1
(p)
Pellet composed of
Metal (b) of
" 3.1V-1.7V
V.sub.6 O.sub.13 *.sup.1
Lithium Comparative
Example 1
(q)
Pellet composed of
Metal (d) of
" 3.0V-2.0V
polyaniline*.sup.3
Lithium Comparative
Example 2
__________________________________________________________________________
In Table 7:
*.sup.1 Described in Denki Kagaku (Electrochemistry), Vol. 54, 691 (1986)
*.sup.2 Described in U.S. Pat. No. 4,758,484
*.sup.3 Described in JPA-63-463233
*.sup.4 Described in JPA-62-143373
*.sup.5 Described in JPA-61-200667
*.sup.6 Described in JPA-2-219823
*.sup.7 Described in JPA-2-255770
EXAMPLE 8
Each of the Tan-3 type (size AA) batteries shown in FIG. 4 were prepared
using each of the organic solid electrolytes prepared in Example 1 (or
Example 4). As the positive active material, the positive electrode
material (0.75 AH) composed of V.sub.6 O.sub.13 described in Denki Kagaku
(Electrochemistry), Vol. 54, 691 (1986) was used, as the negative active
material, metal lithium (1.5 AH) was used, organic solid electrolyte (9)
prepared in Example 1 (or Example 4) was used between the positive
electrode pellet and the negative electrode pellet.
On the Tan-3 type (size AA) lithium battery, a charging and discharging
test was carried out in the range of from 3.1 V to 1.7 V at a current
density of 1.1 mA/cm.sup.2. The result is shown in curve (h) of FIG. 5 as
the change of the charging and discharging capacity.
By following the same procedure as above using the components shown in
Table 8, lithium batteries (i) to (n) shown in Table 8 were prepared and
the charging and discharging test was carried out on each battery.
The test results were as follows. That is, Nos. (h) to (k) in Table 8
correspond to curves (h) to (k) shown in FIG. 6 and Nos. (l) to (n) shown
in Table 7 correspond to curves (l) to (n) shown in FIG. 6.
COMPARATIVE EXAMPLE 13
Using solid electrolytes prepared in Comparative Examples 3 and 4 (or
Comparative Examples 9 and 10), lithium batteries (r) and (s) shown in
Table 8 were prepared by the same manner as in Example 8 and the charging
and discharging test was carried out under the same condition described in
Table 8. The test results were curves (r) and (s) in FIG. 5 and curves (r)
and (s) in FIG. 6, respectively.
As is clear from FIG. 5 and FIG. 6, it can be seen that the batteries using
the organic solid electrolytes of this invention are excellent in the
change of charging capacity as compared to the batteries using the solid
electrolytes in Comparative Examples 3 and 4 (or Comparative Examples 9
and 10).
(The same results were obtained using the organic solid electrolytes
prepared in Example 4 and Comparative Examples 9 and 10.)
TABLE 8
__________________________________________________________________________
Positive Electrode Negative Electrode
Current
Changing and
Active Material Active Material
Electrolyte
Density
Discharging
No.
(capacity, 0.75 AH)
(capacity, 1.5 AH)
(17 mm.phi.)
(mA/cm.sup.2)
Depth
__________________________________________________________________________
(h)
Positive electrode material
Li--Al Alloy
(2) of
1.1 3.1V-1.7V
composed V.sub.6 O.sub.13 *.sup.1
Example 1
(i)
Positive electorde material
" (26) of
" 3.3V-1.9V
composed of .gamma.-.beta.-MnO.sub.2 + Li.sub.2 MnO.sub.3 *.sup.2
Example 3
(j)
Positive electrode material
Metal (7) of
" 3.2V -1.8V
composed of amorphous V.sub.2 O.sub.5 *.sup.3
Lithium Example 1
(k)
Positive electrode material
Metal (15) of
" 2.4V-1.1V
composed of MoS.sub.2 *.sup.4
Lithium Example 2
(l)
Positive electrode material
Metal (29) of
" 2.2V-1.5V
composed of TiS.sub.2 *.sup.5
Lithium Example 3
(m)
Positive electrode material
Li--Al Alloy
(31) of
" 3.0V-2.0V
composed of polyaniline*.sup.6
Example 3
(n)
Positive electrode material
Metal (23) of
" 3.3V-1.7V
composed of polypyrrole*.sup.7
Lithium Example 2
(r)
Positive electrode material
Metal (e) of
" 3.1V-1.7V
composed of V.sub.6 O.sub.13 *.sup.1
Lithium Comparative
Example 3
(s)
Positive electrode material
Metal (g) of
1.1 3.3V-1.9V
composed of .gamma.-.beta.-MnO.sub.2 + Li.sub.2 MnO.sub.2 *.sup.2
Lithium Comparative
Example 4
__________________________________________________________________________
In Table 8:
*.sup.1 Described in Denki Kagaku (Electrochemistry), Vol. 54, 691 (1986)
*.sup.2 Described in U.S. Pat. No. 4,758,484
*.sup.3 Described in JPA-61-200667
*.sup.4 Described in JPA-61-64083
*.sup.5 Described in JPA-62-222578
*.sup.6 Described in JPA-2-219823
*.sup.7 Described in JPA-2-255770
As described above, according to this invention, an organic solid
electrolyte having an excellent ionic conductivity, showing a good film
forming property, and not causing liquid extrusion can be obtained.
Since the organic solid electrolyte of this invention uses a porous film
having large pore sizes and a high molecular compound having an aromatic
ring at the side chain, the film strength is very strong and even when the
porous film is impregnated with a large amount of a nonprotonic polar
solvent, the film strength is above a practical level. Also, since the
pore sizes are large, the interfacial resistance can be sufficiently
reduced.
That is, according to this invention, an organic solid electrolyte having a
performance capable of satisfying all the ionic conductivity, the film
forming property, and the interfacial resistance can be provided.
While the invention has been described in detail and with reference to
specific embodiments thereof, it will be apparent to one skilled in the
art that various changes and modifications can be made therein without
departing from the spirit and scope thereof.
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